Modems for digital communications systems are designed to cope with various channel impairments. An essential element of the modem is the start-up process in which modem parameters such as equalizer taps, carrier frequency error, timing error, and gain setting, are estimated in order to provide the required modem performance.
In the prior art, two training modes are used: 1) using a known transmitted data sequence; 2) or using the transmitted information data without any prior knowledge of the value of the transmitted data. The latter mode is known as a blind start-up.
In the prior art, it is difficult to perform a blind start-up process, with limited computational resources and to converge to a good initial setting of the modem parameters for channels that exhibit severe linear distortion which gives rise to severe inter-symbol interference (ISI), and channels that suffer from severe narrow-band interference.
Therefore, there is a need in the art to provide a solution for the blind start-up process of a receiver in the context of digital communications signals in the presence of severe ISI and severe narrow-band interference. There is an additional need in the art to provide relief from ISI and severe narrow-band interference for conventional blind and non-blind modems.